Documentation inheritance issue with included extension modules

Problem Description

Functions defined in extension modules (like FoldableExtensions) lose their documentation when included in user-facing modules like List and Array. This creates a significant gap in the generated API documentation where core utility functions appear completely undocumented.

Concrete Example

The all function is defined in src/extensions/Relude_Extensions_Foldable.re with comprehensive documentation:

/**
Indicates if all items in the foldable satisfy the given predicate.
*/
let all: 'a. ('a => bool, F.t('a)) => bool =
  (f, xs) => F.fold_left((v, x) => v && f(x), true, xs);

However, when users access this via List.all or Array.all (through the include statement in *_Instances.re files), the generated HTML documentation shows the function signature but no documentation text.

Affected Functions

All functions from FoldableExtensions that users interact with through collection modules:

• all, any - predicate checking
• contains, containsBy - membership testing
• length, size, count - counting
• find, findWithIndex - searching
• forEach, forEachWithIndex - iteration
• min, max, minBy, maxBy - extrema
• toList, toArray - conversions
• Plus functions from other extension modules (MonoidExtensions, EqExtensions, etc.)

Estimated impact: ~20+ core utility functions per collection type appear undocumented.

How to Verify the Issue

1. Build documentation: make docs
2. Open _build/default/_doc/_html/relude/Relude/List/index.html
3. Search for id="val-all" - you'll find the function signature but no <div class="spec-doc"> section
4. Compare with _build/default/_doc/_html/relude/Relude/Extensions/Foldable/FoldableExtensions/index.html where the documentation is complete

Root Cause Analysis

This is a fundamental limitation of ReasonML/OCaml's module system:

1. Module functors like FoldableExtensions(F) define documentation at the functor level
2. Include statements (include Relude_Extensions_Foldable.FoldableExtensions(Foldable)) copy function implementations but not odoc comments
3. Generated documentation only sees the final module signature, not the source of included functions
4. IDE tooling and Context7-style documentation crawlers see functions without their original documentation

Impact on Context7 Integration

This directly affects issue #353's goal of Context7 integration because:

• Context7 crawls the generated documentation (HTML/markdown)
• Missing documentation means core utility functions appear as undocumented in AI/LLM contexts
• Users get incomplete API information when using Claude Code or similar tools
• Significantly reduces the value of Relude in AI-assisted development

Potential Solutions

Option 1: Manual Documentation Duplication

Approach: Copy documentation comments to each inclusion site
Pros: Guaranteed to work with current tooling
Cons: Maintenance burden, documentation drift risk, violates DRY principle

Option 2: Preprocessing Script Solution

Approach: Build-time script that copies documentation from extension modules to included locations
Pros: Automated, maintains single source of truth
Cons: Complex build process, needs custom tooling

Option 3: odoc Attribute Workarounds

Approach: Use [@@@ocaml.doc] attributes or similar odoc directives
Pros: Works within existing system
Cons: Limited effectiveness for included modules, still experimental

Option 4: Upstream Tooling Improvements

Approach: Contribute to odoc to support documentation inheritance
Pros: Benefits entire OCaml ecosystem
Cons: Long-term solution, no immediate fix

Recommended Approach for Context7

For the Context7 integration effort, I recommend Option 2 (preprocessing script) because:

1. Immediate fix: Can be implemented as part of the documentation generation pipeline
2. Automation: No ongoing maintenance burden once implemented
3. Context7 compatibility: Generates properly documented HTML/markdown that Context7 can crawl
4. Reversible: Can be removed if upstream solutions emerge

Implementation Plan

1. Create scripts/copy-extension-docs.js that:
   • Parses extension module .re files for documentation comments
   • Identifies where those functions are included in collection modules
   • Copies documentation to a temporary location before odoc generation
2. Integrate into documentation generation workflow (make docs)
3. Test with Context7 submission to verify improved documentation quality

Success Criteria

• All ~20+ affected functions show proper documentation in generated HTML
• Context7 can successfully index comprehensive Relude API documentation
• Zero documentation gaps for core utility functions accessed through List/Array/etc.
• Automated solution requires no manual maintenance

This issue represents a significant barrier to AI/LLM accessibility of the Relude library and should be prioritized for the Context7 integration effort.